Effects of ULF waves on the Earth’s radiation beltshttp://www.ucl.ac.uk/mssl/space-plasma-physics/nuggets/mssl-plasma-nuggets/pokhotelov-ulf-radiation-beltRelativistic particles with
energies of up to few Megaelectron Volts are trapped by the Earth’s main
magnetic field in the regions known as Van Allen radiation belts. The intense
radiation environment imposes danger for satellite operations and needs to be
forecasted and modelled using numerical simulations and data assimilation. Electromagnetic
ultra low frequency (ULF) oscillations in the range of 150-600 s periods, produced
by the interaction between solar wind and the Earth’s magnetosphere, play a
substantial role in the acceleration, transport and loss of radiation belt
particles. Properties of ULF waves need to analysed to improve the modelling of
radiation belts.Colin Forsyth2016-11-24T15:42:22ZSubstructures within a Dipolarization Front Revealed by High-temporal Resolution Cluster Observationshttp://www.ucl.ac.uk/mssl/space-plasma-physics/nuggets/mssl-plasma-nuggets/yao-df-electronsA Dipolarization Front (DF) is usually considered as the leading
edge boundary of a reconnection outflow in the magnetotail, and is
characterised by a dramatic magnetic field enhancement, typically on B z component in GSM
coordinates. This B z ramp
usually lasts for a few seconds, which is comparable to the spin period of a
Cluster or a THEMIS spacecraft.Colin Forsyth2016-11-04T14:39:25ZWhat effect do substorms have on the radiation belts?http://www.ucl.ac.uk/mssl/space-plasma-physics/nuggets/mssl-plasma-nuggets/forsyth-substorms-radbeltThe Van Allen radiation belts are a torus of high-energy charged particles trapped on magnetic field lines at the Earth. Consisting mainly of near-relativistic electrons, these belts stretch out from a few thousand kilometres altitude to around geosynchronous orbit and pose a very real hazard to satellites flying through or inhabiting this space. One of the mysteries of the radiation belts is how they get there - most of the plasma in the magnetosphere or coming off the Sun is at much lower energies. One theory is that dynamic events in the magnetosphere known as substorms, that also result in bright auroral displays, might energise particles in the magnetosphere or provide a mechanism by which particles might be accelerated to these exceptionally high energies.Colin Forsyth2016-10-18T15:44:37ZULF Waves above the Nightside Auroral Oval during Substorm Onsethttp://www.ucl.ac.uk/mssl/space-plasma-physics/nuggets/mssl-plasma-nuggets/ulf-waves-monographThe first indication of substorm onset is a sudden brightening of one of the quiet arcs lying in the midnight sector of the oval, and an explosive auroral displays covering the entire night sky follows. In space, this corresponds to a detonation that releases a huge amount of energy stored in the stretched night-time magnetic fields and charged particles. This chapter reviews historical ground-based observations of electromagnetic waves and their role in detonating the substorm, and highlights new research linking these electromagnetic waves explicitly to substorm onset itself. The chapter focuses on the properties of ultra-low frequency (ULF) electromagnetic waves that are seen in two-dimensional images of the aurora and discusses a wider range of physical processes that could be responsible for the azimuthally structured auroral forms along the substorm onset arc immediately before it explosively brightens. Colin Forsyth2016-04-11T08:32:15ZStudent Sounding Rockets to train the next generation of space scientistshttp://www.ucl.ac.uk/mssl/space-plasma-physics/nuggets/mssl-plasma-nuggets/canorockThe Canada-Norway Student Sounding Rocket
(CaNoRock) program is a multi-national, multi-university collaboration to train
undergraduate students in space science or engineering, and to recruit them
into space-related graduate studies or industry.Colin Forsyth2016-04-11T08:28:36ZA New Technique for Determining Substorm Onsets and Phases from Indices of the Electrojet (SOPHIE)http://www.ucl.ac.uk/mssl/space-plasma-physics/nuggets/mssl-plasma-nuggets/forsyth-substorms-SOPHIESubstorms are a fundamental mode of variability of the solar wind-magnetosphere-ionosphere system. Previous studies have shown that they can process over 1000 TJ of captured solar wind energy and, in so doing, divert magnetospheric currents through the ionoshpere. This diversion of currents results in a distinct signature in ground-based magnetometer measurements at auroral latitudes. In a new paper, Forsyth et al [2015] have developed a technique for identifying all parts of a substorm from this ground-magnetometer data.Colin Forsyth2015-12-03T11:03:47ZLightning as a Space Weather Hazardhttp://www.ucl.ac.uk/mssl/space-plasma-physics/nuggets/mssl-plasma-nuggets/lightning-space-weatherUK lightning rates previously have been shown to be influenced by large compressed regions of solar wind known as corotating interaction regions (CIRs). CIRs are often co-located with the heliospheric current sheet (HCS) at 1AU. A catalogue of all HCS crossings from 2000 to 2007 is computed using the change in the magnetic field direction. The average lightning rates (RL; from the UK MetOffice’s radio network) and average thunder days (RTH; from audio records) were then computed for 40 days either side of the HCS crossing. These results are shown in the top two rows of the figure. 13.5-and 27-day peaks in thunderstorm activity is observed corresponding to the regularity of HCS crossings of the Earth as they rotate around with the Sun.Colin Forsyth2015-12-02T10:49:07ZA physical explanation for the magnetic decrease ahead of dipolarization frontshttp://www.ucl.ac.uk/mssl/space-plasma-physics/nuggets/mssl-plasma-nuggets/yao-magnetic-dipBursty Bulk Flows (BBFs) are intervals of fast Earthward plasma and magnetic flux transport in the plasma sheet, and are usually considered as the most important carriers of mass and energy towards the near-Earth region. A BBF consists of one or more individual flow bursts (FBs) [Angelopoulos et al., 1992]. Both the plasma velocity and the north-south component of the magnetotail’s magnetic field inside the BBF are significantly larger than in the surrounding region. They carry a stronger magnetic field and current density on their leading edge than in the surrounding magnetotail. The front of the BBF is often associated with a sharp increase in the northward magnetic field component B_z and is thus known as the dipolarization front (DF) [Nakamura et al., 2002; Sergeev et al., 2009]. This is usually a kinetic-scale structure of width of the order of an ion gyro-radius, i.e. ~1000km.Colin Forsyth2015-10-29T09:55:11ZStatistical characterisation of the growth and spatial scales of the substorm onset archttp://www.ucl.ac.uk/mssl/space-plasma-physics/nuggets/mssl-plasma-nuggets/kalmoni-growth-auroral-arcsDuring southward IMF reconnection on the dayside leads to a build up of magnetic energy in the tail. As flux is piled into the tail the configuration becomes unstable leading to an explosive release in magnetic energy, termed a substorm. The rearrangement of the magnetic field is accompanied by highly dynamic substorm aurora. Colin Forsyth2015-10-12T09:13:31ZInfluence of solar wind variability on magnetospheric plasma waveshttp://www.ucl.ac.uk/mssl/space-plasma-physics/nuggets/mssl-plasma-nuggets/pokhotelov-ulf-solar-windSolar wind impacts the Earth’s magnetic
cavity driving various waves and instabilities inside the magnetosphere. The
waves in the range of few mHz (ultra low frequency range, ULF) are particularly
important for the dynamics of radiation belts, the populations of energetic
particles trapped inside the Earth’s magnetosphere. The physical mechanisms
behind driving ULF wave power are not fully understood but they are known be
strongly dependent on the upstream solar wind conditions. The time-average
solar wind parameters, such as average solar wind speed and density, are
typically used to characterise the upstream solar wind conditions. In this
work, the alternative approach is taken and the solar wind conditions are
characterised by the dynamic variability of solar wind parameters,
statistically quantified by their standard deviations. For the statistical
study, the nine-year dataset of GOES satellite observations at the
geostationary orbit is processed to characterise the magnetospheric ULF wave
power, while the variability of solar wind is characterised using solar wind
data from the Lagrangian L1 point. It is demonstrated that the magnetospheric
wave power in ULF frequency range is the most sensitive to the variability of
interplanetary magnetic field vector rather than variabilities of other solar
wind parameters (plasma density, solar wind speed and temperature). The work
results from collaboration between MSSL, NASA Goddard Space Flight Center and
the University of Alberta.Colin Forsyth2015-06-10T12:40:38Z